Comments

Easy enough to do. Get a bunch of stacks of colored square post-its, and convert a gif image of your favorite character into 8-bit color in Gimp. Resize the image to match the "pixel count" of your library window and print the image on a sheet of paper as an assembly guide.

What'd be more cool is to set up a camera on a permanent mount across the street, and build a sequence of post-it images on the window over the course of several weeks as animation. Like Calvin kicking Garfield's butt.